This is a Phase I study to evaluate the safety and tolerabilty of a new multi-drug resistance modulator GG918 in combination with doxorubicin. In addition, we will try and determine if GG918 alters the doxorubicin pharmacokinetics and detemine surogate markers (Tc99m sestamibi scans and rhodamine retention assays) may be used to measure functional p-gp blockade.